Joint for protecting underground metal pipes from stray electric currents

摘要

653,127. Pipe joints. COMPAGNIE DE PONT-A-MOUSSON. July 27, 1948, No. 20050. Convention date, Jan. 27. [Class 99(i)] In an electric insulating joint for metal pipes 1, 1a, a cylindrical spigot 3 on the pipe 1a is fitted in a bell-mouthed socket on the pipe 1, a washer 5, e.g. of rubber, which has two opposed circular tongues 11, 12 is inserted, and the washer is compressed by a clamping collar 7 fixed to the bell. An insulating ring 16, e.g. of tarred wood or a thioplastic material covered by carbon black, is positioned between the end faces of the pipes 1, 3 and may be made up of a number of laminations. For conveying corrosive fluids the washer may be tipped with, made from, or encased in, a refractory material. The Specification as open to inspection under Sect. 91 comprises also a modification in which a ring L-shaped in crosssection is fitted on the end of the spigot, and a fusible insulating material is poured into the space between the spigot and socket. This subject-matter does not appear in the Specification as accepted.